Microscope

ABSTRACT

A microscope having a night vision apparatus, which apparatus can be impinged upon by beam paths proceeding from a specimen or object to be observed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German patent application 10 2007019 335.3 filed Apr. 24, 2007, which is incorporated by referenceherein.

FIELD OF THE INVENTION

The present invention relates to a microscope, in particular to astereomicroscope.

BACKGROUND OF THE INVENTION

Conventional microscopes, e.g. surgical microscopes, comprise apermanently incorporated illumination system with which a specimen orobject to be viewed is illuminated. The illumination system can beembodied as a reflected-light and/or transmitted-light system.

Highly sensitive specimens exist, however, that can be damaged byvisible light, UV light, or even IR light. An example that may be givenhere is the human eye that is being viewed by means of a microscope inthe context of an ophthalmic operation.

The present invention strives to make available a microscope, inparticular a surgical microscope, in which damage to the specimen beingobserved as a result of the light used for illumination of the specimenis minimized or entirely avoided.

A microscope having the features of claim 1 is proposed for thispurpose.

With a microscope according to the present invention, the lightintensity necessary for observation or for sufficient illumination of aspecimen can be significantly reduced as compared with conventionalsolutions. Night vision apparatuses usable according to the presentinvention are available relatively economically. The solution accordingto the present invention makes a significant contribution towardreducing stress on light-sensitive specimens that are being examinedunder a microscope. The solution according to the present invention ismoreover physically small and compact, so that it is readily usable fornumerous applications. In particular, night vision device canadvantageously be integrated into the microscope housing.

A night vision apparatus can be introduced into the normal beam path ofa microscope, i.e. for example positioned on an optical axis defined bya main objective and/or a zoom system. It is likewise possible to coupleout additional beam paths for a night vision apparatus. A beam pathcoupled out in this fashion can be delivered to a suitably positionednight vision apparatus. An image generated by means of the night visionapparatus can then be displayed on a monitor. It is likewise conceivableto superimpose the image generated by the night vision apparatus backonto the normal beam path of the microscope. Depending on thesuperimposition location, a magnification generated in the normal beampath must be compensated for in the image provided by the night visionapparatus.

The microscope is embodied in particular as a stereomicroscope. Theinvention proves advantageous in particular in connection with thestereoscopic viewing of a specimen, since good stereoscopic observationis possible here even with very dim or weak light.

Advantageous embodiments of the microscope according to the presentinvention are the subject matter of the dependent claims.

Stereomicroscopes of this kind are usable in particularly advantageousfashion as surgical microscopes.

In this connection, reference may be made to the following: Inprinciple, any number of night vision apparatuses can be provided for amicroscope according to the present invention. For example, two nightvision devices can be provided for a stereomicroscope. These nightvision apparatuses can be introduced into the respective stereoscopicobservation channels, or can be impinged upon by further beam pathsproceeding from a specimen to be observed.

It is likewise possible to provide only a single night vision apparatusfor a number of beam paths, for example for both normal observation beampaths of a stereomicroscope, and to obtain images sequentially, forexample by means of a suitable time-related control system, for therespective beam paths or observation channels. Images acquired shortlyafter one another (sequentially) can be viewed stereoscopically, withoutsubstantial degradation or perceptible time delay for an observer, bybeing presented, for example, on an autostereoscopic display or on adisplay having polarization display means.

According to a preferred embodiment of the invention, the night visionapparatus is placed downstream and/or upstream from a zoom system of themicroscope. An upstream positioning, i.e. for example between the mainobjective and zoom system of a microscope, proves particularlyadvantageous, since no attenuation of the limited spectral range that istypically essential for a night vision apparatus occurs as a result ofthe optical properties of the zoom system (absorption or lightattenuation). A superimposition of the image generated by the nightvision apparatus with the normal observation beam paths of themicroscope can likewise occur before and/or after the zoom system.

A superimposition of the image generated with the night vision apparatusonto the normal beam path or paths of the microscope is, as mentioned,advantageous. Usefully provided for this purpose is a superimpositiondevice with which an image generated by a night vision apparatus can besuperimposed onto a normal beam path of the microscope. With such asuperimposition, a high-contrast image can be generated in particular indim light conditions. It is possible in this connection, for example, toelectronically process images generated by the one or more night visiondevices. Edge emphasis or intensification, as well as color modificationor color coding, may be mentioned here by way of example. The term“normal” beam paths refers here to beam paths that do not impinge on thenight vision device, but instead pass through the usual components of amicroscope, namely e.g. the main objective, zoom system, eyepiece, etc.

Usefully, a superimposition device of this kind comprises means formagnifying or enlarging an image generated by the night visionapparatus. With such means it is possible to introduce the imagegenerated by the night vision apparatus back into the normal beam patheven after a magnification system, for example the zoom system.

According to a preferred embodiment of the microscope according to thepresent invention, generation of a respective image by way of respectivenight vision apparatuses occurs for two observation channels of astereomicroscope, the generated images being inputted into a connectedcomputer or one integrated into the microscope and presentedstereoscopically on a screen. This feature permits additional oralternative viewing, on the screen, of a specimen to be observed.

It proves advantageous to provide at least one shutter that isextendable into and retractable from the beam paths. With such shutters,a user of the microscope can, for example, select or switch back andforth between a direct observation of the image through the observationchannel or channels of the microscope and an image generated by a nightvision apparatus, presented on a monitor, and reflected into theobservation channel or channels of the microscope. A superimposedobservation of these two aforesaid images can also be implemented withappropriate positioning of the shutters or shutter elements.

According to a further preferred embodiment of the microscope accordingto the present invention, an illumination device can be selectablyswitched in. An illumination device of this kind can, for example, beswitched in for the observation of non-sensitive specimens. Anillumination device of this kind can also be quickly switched on, forexample, in an emergency. When an illumination device is switched on, anautomatic switching off of the respectively provided night visionapparatuses is also conceivable.

According to a further preferred embodiment of the microscope accordingto the present invention, deflection elements having a variablereflectivity or transmissivity, which can be impinged upon by therespective beam paths, are provided. The concept of “variability” isalso intended to encompass the possibility of displacing a beam splitterentirely out of a beam path. This would thus mean a decrease inreflectivity to zero. Stepless variability is also, however, intended tobe encompassed in the same fashion. Stepless variability is achievable,for example, by means of micromirror arrays that are usable selectablyas fully reflective mirrors, partially transparent, or semitransparentmirrors (beam splitters), or even as entirely transmissive elements.

The invention and its advantages will be further explained below withreference to exemplifying embodiments that are illustrated in theappended drawings. It is understood that the features of the inventiondiscussed and yet to be discussed are usable not only in the respectivecombination indicated, but also in other combinations or in isolation,without departing from the context of the present invention. Differentembodiments are also, in particular, partially or completely combinable.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained further with reference to theappended drawings, in which:

FIG. 1 is a schematic side view of a first preferred embodiment of amicroscope according to the present invention;

FIG. 2 is a schematic side view of a second preferred embodiment of amicroscope according to the present invention;

FIG. 3 is a schematically simplified plan view of a preferredarrangement of the observation channels or beam paths explainedaccording to FIG. 1; and

FIG. 4 a schematic side view of a third preferred embodiment of amicroscope according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The microscope depicted in FIG. 1 is embodied as a stereomicroscope andlabeled 100 in its entirety. Stereomicroscope 100 serves, in the exampledepicted, as a surgical microscope for observing an eye 1 of a patient.Stereomicroscope 100 comprises two observation channels 102, 104 inorder to enable stereoscopic observation of eye I by a user 29.

Beam paths 50, 52, 54, 56 emerging from eye 1 first strike a mainobjective 3. Observation channels 102, 104 are arranged behind mainobjective 3 as viewed from the observed specimen or eye 1, so that beampath 50 proceeds through observation channel 102, and beam path 52through observation channel 104. Observations channels 102, 104 proceedthrough a zoom system 4 configured with two channels, and through abinocular tube 5. Zoom system 4 and binocular tube 5 each comprise anumber of lenses. Binocular tube 5 is embodied in the usual way witheyepieces 5 a, 5 b.

Main objective 3, zoom system 4, and binocular tube 5 are arranged in amicroscope housing 2.

Observer 29, in particular a surgeon, can stereoscopically observe eye 1by observing beam paths 50, 52 that, as mentioned, proceed through mainobjective 3, zoom system 4, binocular tube 5, and eyepieces 5 a, 5 b.

The stereomicroscope depicted in FIG. 1 comprises two night visionapparatuses 20 a, 20 b. By means of these night vision apparatuses 20 a,20 b, an observation of eye 1 is possible even in poor viewingconditions or with dim or absent illumination, as will be explainedbelow.

Further beam paths 54, 56 emerging from eye 1 strike deflection elements80 and 82, respectively after passing through main objective 3 inmicroscope housing 2. Beam path 54 is directed via deflection element80, which is preferably provided as a mirror, into first night visionapparatus 20 a. Embodied between deflection element 80 and night visionapparatus 20 a are a beam splitter element 18 and an imaging system 19(depicted for the sake of simplicity as a lens). The function of beamsplitter element 18 will be explained below. Night vision apparatus 20 acomprises, in a manner known per se, a low-light amplifier 21. In this,light (i.e.

beam path 54) striking a photocathode 202 on, for example, entry side201 triggers electrons that, accelerated by a high voltage in a vacuum204, strike a luminous screen 206 on the opposite side and theregenerate an image.

Be it noted that the embodiment of a night vision device or low-lightamplifier in the manner just described represents only one of severalpreferred embodiments. It is additionally possible to use, as nightvision apparatuses, CCD or CMOS image sensors that, for example, respondto IR radiation of certain wavelengths or to another suitable wavelengthregion (e.g. UV region). Utilization of such image sensors, which arealso used in conventional digital cameras or digital film cameras,proves to be particularly compact.

Analogously thereto, second night vision apparatus 20 b is impinged uponby the further beam path 56 emerging from the eye, which path isdeflected by a further deflection element 82. An imaging system (onceagain depicted in simplified fashion as a lens) is likewise providedbetween deflection element 82, likewise preferably embodied as a mirror,and second night vision apparatus 20 b.

Second night vision apparatus 20 b, analogously to the first, likewisecomprises a low-light amplifier 21. Second night vision apparatus 20 banalogously generates an image on a luminous screen 206.

According to a first preferred embodiment, the images generated by thetwo night vision apparatuses 20 a, 20 b can be digitized and deliveredvia conductors 27 a, 27 b to a computer 28, where they are processableto yield a stereoscopic image that can be presented on a monitor 30.

Alternatively or in addition to an observation via observation channels102, 104 of the microscope, observer 29 can thus stereoscopically view,on monitor 30, eye 1 that is to he observed.

Alternatively or in addition to this stereoscopic image processing incomputer 28, the images generated by the two night vision apparatuses 20a, 20 b can also be reflected into observation channels 102, 104. Thismakes possible a superimposition of the images produced in observationchannels 102, 104 and the images generated by the night visionapparatuses.

Advantageously, this superimposition is accomplished by means ofsuperimposition devices 6, 7 to which the respective signals and imagesof night vision apparatuses 20 a, 20 b are delivered via conductors 37a, 37 b. These superimposition devices each comprise an image processingdevice 6 and a semitransparent mirror 7 positioned in observationchannels 102, 104 or beam paths 50, 52. Image processing devices 6 eachcomprise a presenting display that transfer the respective images to bepresented, via further imaging systems 19 (once again depicted as alens) onto semitransparent mirror 7. Because this superimposition occursbehind zoom system 4 as viewed from objective 1 or main objective 3, theactual magnification experienced by beam paths 50, 52 as a result of thezoom system must be taken into account in image processing devices 6.For this purpose, zoom system 4 comprises sensors that sense the'currentmagnification of the zoom system and transfer it to image processingdevices 6.

It is further evident from FIG. 1 that the observation angles of beampaths 50 and 54, and 52 and 56, are different in each case. Becausethese beam paths, or images generated from them, are superimposed on oneanother in superimposition devices 6, 7, these angle differences orposition differences are usefully also compensated for in imageprocessing devices 6.

There arc several possibilities in this context: For example, it isconceivable to minimize the angles between beam paths 50 and 54, and 52and 56 as much as possible in order to minimize the distances betweenthe respective deflection elements and the beam paths 50, 52 proceedingthrough the zoom system. For this purpose, deflection devices 80, 82 canalso be embodied displaceably perpendicular to the beam paths 50, 52proceeding through the zoom system, as indicated by double arrows 80 a,82 a.

It is likewise advantageously possible to reflect the images generatedby night vision apparatuses 20 a, 20 b into beam paths 50, 52 below thezoom system, i.e. for example between main objective 3 and zoom system4. In this case, computational compensation for the magnification ofzoom system 4 can be omitted.

A further possibility for the positioning of deflection elements or beamsplitter devices for selective impingement upon observation channels102, 104 and/or night vision devices 20 a, 20 b is depicted with dashedlines in FIG. 1 and labeled 90, 92.

This involves beam splitter elements 90, 92 that are introducible intoobservation channels 102, 104 in order to make available a beam paththrough observation channels 102, 104 and/or an impingement upon nightvision devices 20 a, 20 b. Beam splitter elements 90, 92 are provided,for example, as semitransparent mirrors that split beam paths 50 and 52into partial beam paths through zoom system 4 and night visionapparatuses 20 a, 20 b respectively. A solution of this kind has theadvantage, as compared with the provision of mirrors 80, 82, that theobservation angle for the beam paths through the zoom system and throughnight vision apparatuses 20 a, 20 b is the same in each case, so thatcomputational compensation for different observation angles, for examplein image processing device 6, is not necessary.

Beam splitter elements 90, 92 can furthermore also be embodied, forexample, as micromirror arrays whose individual micromirrors arepositionable so that both complete reflectivity and completetransmissivity of beam splitter elements 90, 92 can be established. Withcomplete reflectivity, beam paths 50, 52 are deflected in their entiretyinto the respective night vision devices 20 a, 20 b. With completetransmissivity, beam paths 50, 52 are directed completely into zoomsystem 4 and into the optical components subsequent thereto

It is likewise conceivable to provide deflection elements 80, 82 as wellas beam splitter elements 90, 92 together in a microscope, and use themalternatively or also simultaneously.

FIG. 2 depicts a further preferred possibility for positioning the nightvision apparatuses. By means of beam splitters 13, for examplesemitransparent mirrors, that are provided behind zoom system 4 (i.e.between zoom system 4 and binocular tube 5), portions of beam paths 50,52 are deflected and delivered to night vision apparatuses 20 c, 20 d,respectively. The latter function analogously to night visionapparatuses 20 a, 20 b, and make a suitable image available to computer28 via conductors 35 a, 35 b. As explained above with reference to FIG.1, these images can be processed in computer 28 to yield a stereoscopicimage. These images could, however, also be coupled back intoobservation channels 102, 104 above zoom system 4, i.e. for examplebetween beam splitter 13 and binocular tube 5.

The effort made with the present invention is to keep to a minimum anyillumination of specimen 1 being observed, or ideally to dispenseentirely with illumination of the specimen.

An illumination apparatus 8 depicted in FIGS. 1 and 2 is thereforeprovided merely optionally. This illumination device 8 can be switchedin such a fashion that a minimal illumination for the operation of nightvision apparatuses 20 a to 20 d is made available. For example,illumination device 8 can encompass an infrared lamp that makesavailable a minimal infrared light intensity for reasonable or expedientoperation of night vision apparatuses 20 a to 20 d.

Illumination device 8 can also comprise conventional illumination meansthat can be immediately switched on, for example, in an emergencysituation.

Illumination device 8 is depicted in the exemplifying embodiments ofFIGS. 1, 2 as an incident-light apparatus. For certain applications,e.g. observation of at least partially transparent or semitransparentspecimens, it would likewise be conceivable to provide a correspondingtransmitted-light illumination device additionally or alternativelythereto.

It proves to be advantageous to embody illumination device 8 with adimmer function. With this dimmer function, the quantity of light can beoptimally and steplessly adjusted even for very sensitive specimens.Spectrally selective elements are also advantageously usable in thecontext of illumination device 8, for example to reduce visible lightwith a simultaneous relative elevation in the IR component.

It is evident from FIG. 1 that beam splitter element 18 and deflectionelement 80 possess a dual function. On the one hand they serve toreflect in light from illumination device 8 onto the specimen or eye 1.On the other hand, they serve to deflect beam path 54 onto night visionapparatus 20 a. Beam path 54 is thus largely identical to the beam pathof illumination device 8. A very compact configuration of the nightvision apparatuses and of illumination device 8 in a microscope canthereby be achieved.

Be it noted in this connection that as shown in FIGS. 1 and 2, the nightvision apparatuses and the illumination device are not depicted as beingarranged inside microscope housing 2. This serves merely to make thedepiction illustrative, however. The aforesaid components can bearranged both inside and outside microscope housing 2. The same appliesto image processing devices 6 and/or to computer 28 and/or to monitor30.

Stereomicroscope 100 as shown preferably comprises closing apparatuses28 with which the beam paths can selectably be interrupted depending onobservation preference. Closing apparatuses 27 can be controllablyshifted into and out of the respective beam paths by a user. Be it notedthat the number and positioning of closing apparatuses 27 indicated inthe Figures is selected solely by way of example. Depending on theapplication or requirements, more or fewer closing apparatuses can beprovided at suitable positions.

FIG. 3 depicts in plan view a preferred arrangement of beam paths 50, 52and respective observation channels 102, 104, and of beam paths 54, 56and respective deflection elements 80, 82, in a schematic sectionedview.

As is evident, observation channels 102, 104 and deflection elements 80,82 are arranged in a cross shape around a center axis X. Referring toFIG. 1, this means in illustrative terms that deflection element 82 isrotated into drawing plane Z of FIG. 1, and deflection element 80 isrotated out of drawing plane Z. This action makes it possible to matchthe angle enclosed by beam paths 50, 52 extending through observationchannels 102, 104 to the angle enclosed by beam paths 54, 56 thatimpinge upon deflection elements 80, 82. This measure makes it possibleto minimize the computational effort to be expended, for example inimage processing devices 6, in order to equalize or compensate for thedifferent observation angles of light beams 50, 52, 54, 56. A respectivecomputational 90-degree rotation of the images obtained by night visionapparatuses 20 a, 20 b is usefully performed in this context. With a90-degree rotation of this kind and with angles of equal size betweenlight beams 50, 52 and 54, 56, the computational effort for imageprocessing is very small.

The possibility of using micromirror arrays for beam splitter elements90, 92 was discussed with reference to FIG. 1. Be it noted that all theother beam splitter elements mentioned in the present application, i.e.for example beam splitter elements 18, 7 in FIGS. 1 and 13 in FIG. 2,can also be embodied as micromirror arrays. It is furthermoreconceivable to configure the aforesaid beam splitter elements to beselectably extendable into and retractable from the respective beampaths. In combination with the respective shutter elements 27, aplurality of beam path combinations and variations is thus madeavailable for optimizing a specimen observation depending on specificconditions.

Be it noted that beam splitter elements 90, 92, 18, 7, 13 embodied asmicromirror arrays can also serve as shutters. For example, a beamsplitter element 90 embodied as a micromirror array could, withappropriate positioning of the micromirrors, cause beam path 54 to bedeflected by mirrors 80 into night vision device 20 a, andsimultaneously cause beam path 50 to be completely blocked. With thissetting and with a corresponding setting of beam splitter element 92, anobservation of specimen 1 based only on the images made available bynight vision apparatuses 20 a, 20 b would be made available to user 29.In this case, for example, shutters 27 positioned in observationchannels 102, 104 could be omitted. On the other hand, a correspondingcomplete introduction of beam paths 50, 52 into observation channels102, 104 by appropriate positioning of the beam splitter elementsembodied as micromirror arrays 90, 92 would allow, for example, shutters27 placed ahead of the respective night vision devices 20 a, 20 b to beomitted.

The microscope as depicted in FIG. 4 essentially corresponds to themicroscope depicted in FIG. 1. Like components and features aredesignated with like reference numerals.

According to the microscope as shown in FIG. 4, only one night visionapparatus 20 a is provided for the observation beam paths 54, 56.

Reflection elements 80 and 82 are both positioned in order to directbeam path 54, 56 into the night vision apparatus 20 a.

Thus, a second night vision apparatus, as was used according to theembodiment as shown in FIG. 1, is not necessary according to thisembodiment.

In the embodiment according to FIG. 4, the night vision apparatus 28includes a time-related control system 20 x, by means of which the beams54, 56 can be processed sequentially, in order obtain correspondingsequential images for the respective beam paths for observation channels54, 56.

Such images acquired shortly after one another (sequentially) can beviewed stereoscopically by being presented, for example, on anautostereoscopic display or on a display having polarization displaymeans.

To achieve this, analogously to the first embodiment as shown in FIG. 1,images generated by the night vision apparatus 20 a can be digitized anddelivered by conductors 27 a, 27 b to a computer 28, where they areprocessable to provide a stereoscopic image that can be presented on amonitor 30.

Alternatively or in addition to this stereoscopic image processing incomputer 28, the images generated by night vision apparatus 20 a canalso be reflected into observation channels 102, 104. This makespossible a superposition of the images produced in observation channels102, 104 and the images generated by the night vision apparatus 20 a.

Advantageously, this superposition is accomplished by means ofsuperposition devices 6, 7 to which the respective signals and images ofnight vision apparatus 20 a are delivered via conductors 37 a, 37 b. Fora further description of these superposition devices, it is referred tothe description of the embodiment according to FIG. 1.

It is also possible, analogously to the embodiment of FIG. 1, to usebeam splitter elements 90, 92 in the embodiment of FIG. 4 in order tomake the observation angles of beam paths through the zoom systemcorrespond to those through the night vision apparatus.

PARTS LIST

1 Specimen/object (eye)

2 Housing

3 Main objective

4 Zoom system

5 Binocular tube

5 a, 5 b Eyepieces

6 Image processing device

7 Semitransparent mirror

8 Illumination device

13 Beam splitter (semitransparent mirror)

18 Beam splitter

19 Imaging system

20 a, 20 b, 20 c, 20 d Night vision apparatuses

20 x Control system

21 Low-light amplifier

27 Closing apparatuses (shutters)

27 a, 27 b Conductors

28 Computer

29 Observer (user)

30 Monitor

35 a, 35 b Conductors

37 a, 37 b Conductors

50, 52, 54, 56 Beam paths

80, 82 Deflection elements

80 a, 82 a Double arrows

90, 92 Beam splitter elements (semitransparent mirrors, micromirrorarrays)

100 Stereomicroscope

102, 104 Observation channels

201 Entry side

202 Photocathode

204 Vacuum

206 Luminous screen

1-14. (canceled)
 15. A microscope for observing an object, themicroscope comprising: a first beam path proceeding from the object; anight vision apparatus impinged upon by the first beam path; and asecond beam path proceeding from the object and differing from the firstbeam path, wherein the night vision apparatus is also impinged upon bythe second beam path.
 16. The microscope according to claim 15, whereinthe night vision apparatus includes a time-related control system thatsequentially processes the first and second beam paths to obtain firstand second corresponding sequential images for stereoscopic viewing. 17.The microscope according to claim 16, further comprising: a computer bywhich the first and second sequential images are superimposed onto oneanother to generate a stereoscopic image; and a display connected to thecomputer by which the stereoscopic image is displayed.
 18. Themicroscope according to claim 15, further comprising a superimpositiondevice for superimposing an image generated by the night visionapparatus into an observation channel of the microscope.
 19. Themicroscope according to claim 18, wherein the superimposition deviceincludes an image processing device operable to magnify the imagegenerated by the night vision apparatus.
 20. The microscope according toclaim 15, further comprising a first shutter selectively operable toblock the first beam path and a second shutter selectively operable toblock the second beam path.
 21. The microscope according to claim 15,further comprising at least one deflection element or beam splitterelement impinged upon by at least one of the first beam path and thesecond beam path, the at least one deflection element or beam splitterelement having a variable reflectivity or transmissivity.
 22. Amicroscope for observing an object, the microscope comprising: a firstbeam path proceeding from the object; a night vision apparatus impingedupon by the first beam path; a second beam path proceeding from theobject and differing from the first beam path; and a second night visionapparatus impinged upon by the second beam path; wherein the nightvision apparatus and the second night vision apparatus generate firstand second respective images used for stereoscopic viewing.
 23. Themicroscope according to claim 22, further comprising: a computer bywhich the first and second respective images are superimposed onto oneanother to generate a stereoscopic image; and a display connected to thecomputer by which the stereoscopic image is displayed.
 24. Themicroscope according to claim 22, further comprising a firstsuperimposition device for superimposing a first image generated by thenight vision apparatus into a first observation channel of themicroscope and a second superimposition device for superimposing asecond image generated by the second night vision apparatus into asecond observation channel of the microscope.
 25. The microscopeaccording to claim 24, wherein each of the first and secondsuperimposition devices includes an image processing device operable tomagnify the respective first or second image generated by the associatednight vision apparatus.
 26. The microscope according to claim 22,further comprising a first shutter selectively operable to block thefirst beam path and a second shutter selectively operable to block thesecond beam path.
 27. The microscope according to claim 22, furthercomprising at least one deflection element or beam splitter elementimpinged upon by at least one of the first beam path and the second beampath, the at least one deflection element or beam splitter elementhaving a variable reflectivity or transmissivity.